The purpose of this project is to study chemical carcinogen-induced DNA repair in cell strains derived from patients with various genetic diseases showing an enhanced frequency of malignancy. Such investigations can determine if these cells are deficient in their ability to repair DNA damage and if such deficiencies can be correlated with the increased probability of cancer in these patients. The role played by DNA repair mechanisms in an organism's ability to tolerate certain levels of DNA damage can be important in assessing the relative carcinogenicity of particular compounds. Also, these studies can yield information about different classes of DNA lesions induced by chemical carcinogens and whether or not the type of lesion induced can be correlated with the ability of different cell strains to repair damage induced by particular chemical agents. The effects of inhibitors of DNA synthesis on cellular repair parameters are being examined in order to obtain useful information about possible enzymes or DNA structures necessary for repair.